Reactions of trimethylsilyl-derived iodohydrins of the type R1R2CH–CH(I)OTMS, with electron-rich olefins, and the effects of certain factors on these reactions, were studied. The trimethylsilyl-derived iodohydrins were obtained in situ by reacting R1R2CH–CHO (R1 = R2 = H; R1 = H, R2 = alkyl, phenyl) with TMSI. The corresponding trimethylsilyl enol ether derivatives (R1R2C&═CH–OTMS), and 1,1-diarylethylenes were the olefins used. Aldehydes of the type RCH2–CH&═O reacted smoothly in the presence of TMSI to yield the condensation product RCH2–CH&═C(R)–CH&═O. Both RCH(–CH&═CAr2)2 and the cyclic acetal 5 were obtained as main products of the RCH&═O–TMSI–CH2&═CAr2 reaction system, depending on the [RCHO] ∶ [TMSI] ∶ [CH2&═CAr2] concentration ratio. The mechanisms of formation for the various main products and by-products are discussed. TMSI substitutes, formed by reacting Me3SiCl with each of several Lewis acids, were also used.
|Number of pages||5|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|State||Published - 24 Jan 2002|